Greenhouse owners generally spike their air to 1200-1500ppm CO2. That's the compromise between best cost and best for the plants and is lower than these species evolved in.
As to humans, 400ppm causes zero problems, matter of fact, OSHA says 1000ppm for continuous exposure. NIOSH says 10,000 ppm for a 10 hour work shift.
As to humans, 400ppm causes zero problems, matter of fact, OSHA says 1000ppm for continuous exposure. NIOSH says 10,000 ppm for a 10 hour work shift.
For instance: https://inspectapedia.com/hazmat/Carbon%20_Dioxide_Exposure_...